SimmsFishFence
Eric V
22 February, 2025
1. Introduction
Simms Creek is a small, 3rd order stream that drains an area of ~1,800 ha into the Salish Sea, near Campbell River’s Willow Point neighborhood. The lower reach of Simms Creek (~3 km of channel, east of Dogwood Street), is contained within a narrow urban green way that is bordered by residential properties. From Dogwood Street Road the streams runs for ~ 2 km to the Inland Highway and is protected within Beaver Lodge Lands, upstream of the Inland Highway, >1.5 km of tributary channel is located within private forest lands in various stages of regeneration.
Chum, Chinook, Pink and Coho salmon have all been observed in Simms Creek, as well as Coastal Cutthroat Trout (CCT), Rainbow Trout and steelhead. More recent monitoring (i.e., this dataset), suggest that Coho Salmon (CO) and CCT are the primary species within Simms Creek, both of which are present within the stream year round - though a small number of juvenile Chinook Salmon were identified in 2024.
Greenways Land Trust has supported Simms Creek Stewards for +20 years, including operation of a fish fence near the mouth of the stream since 2008. Juvenile and adult fish moving past the fence are tallied each spring and fall, respectively. The objective of this project is to explore the juvenile fence dataset. All work is being done strictly for fun and out of personal curiosity. Any feedback, input, or support is welcome. Also, I have a soft spot for CCT, so be warned that effort and results will be slightly trout biased. Let’s take a look at what has been completed to date. It’s a tremendous amount of work and all volunteers and supporters should be commended!
2. Fence Operation
2.1. Monitoring Effort
The Simms Creek fish fence has operated annually since 2008, with the exception of 2020 and 2021 when operations were paused due to the COVID-19 Pandemic and in the spring of 2023 when federal employees were on strike.
Spring surveys target out migrating juvenile Coho Salmon but also capture an impressive number of CCT and have even captured some Chinook Salmon. Spring fence monitoring has started as early as April 03, however, most surveys (50%) don’t start until April 18. In each monitoring year, the fence has operated continuously (e.g., sampling occurred at least daily) from April 28 to May 30. Surveys have continued as late as June 13, but most (50%) are terminated by June 06.
Fall surveys to count the number returning adult Coho, Chinook, Chum and Pink Salmon and also intercept a small number of CCT. In the fall, surveys have started as early as September 26, however, most surveys (50%) have started on October 08. In each monitoring year, surveys have occurred continuously (e.g., sampling occurred daily) from October 23 to November 16. Surveys have continued as late as December 10 and no surveys have occurred later than December 02.
Monitoring Effort Tables and Figures
Table 1. Sampling Summary
| Period | Min | Max | Mean | SD | Min | Max | Mean | SD | Min | Max | Mean | SD |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Spring | 41 | 68 | 51.0 | 7.3 | 03-Apr | 28-Apr | 16-Apr | 7.0 | 30-May | 13-Jun | 05-Jun | 4.4 |
| Fall | 35 | 64 | 50.9 | 10.3 | 26-Sep | 23-Oct | 09-Oct | 7.1 | 16-Nov | 10-Dec | 29-Nov | 7.5 |
Table 2. Annual Spring and Fall Trap Operation Periods
| Year | # Days Sampled | Start | End | # Days Sampled | Start | End |
|---|---|---|---|---|---|---|
| 2008 | 41 | Apr-21 | May-31 | 40 | Oct-14 | Nov-22 |
| 2009 | 50 | Apr-19 | Jun-07 | 40 | Oct-14 | Nov-22 |
| 2010 | 42 | Apr-19 | May-30 | 35 | Oct-23 | Nov-26 |
| 2011 | 49 | Apr-19 | Jun-06 | 46 | Oct-18 | Dec-02 |
| 2012 | 50 | Apr-16 | Jun-04 | 50 | Oct-14 | Dec-02 |
| 2013 | 49 | Apr-14 | Jun-01 | 62 | Sep-29 | Dec-01 |
| 2014 | 45 | Apr-24 | Jun-07 | 58 | Oct-04 | Nov-30 |
| 2015 | 52 | Apr-10 | May-31 | 62 | Oct-08 | Dec-08 |
| 2016 | 63 | Apr-03 | Jun-04 | 60 | Oct-07 | Dec-05 |
| 2017 | 68 | Apr-05 | Jun-11 | 56 | Oct-11 | Dec-05 |
| 2018 | 52 | Apr-21 | Jun-11 | 58 | Oct-08 | Dec-04 |
| 2019 | 51 | Apr-18 | Jun-07 | 64 | Oct-08 | Dec-10 |
| 2020 | 0 | COVID |
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| 2021 | 0 | COVID |
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| 2022 | 47 | Apr-28 | Jun-13 | 37 | Oct-11 | Nov-16 |
| 2023 | 0 | DFO Strike |
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45 | Sep-26 | Nov-17 |
| 2024 | 55 | Apr-12 | Jun-05 | 0 |
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2.2 Stream Conditions
During each daily trap visit, volunteers record measures of water temperature, pH, Total Suspended Sediment (TSS), dissolved oxygen, and water level (stage). Mean annual measures of each parameter are presented below for the spring and fall monitoring periods (Table 3 and Table 4, Figure 2).
Stream Conditions Figures and Tables
Table 3. Spring Condition Table
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2008 | 9.5 | 4.0 | 10.5 | 2.8 | 7.1 | 0.3 | 10.8 | 0.8 | 67.8 | 36.8 | 0.2 | 0.0 |
| 2009 | 11.8 | 3.0 | 10.3 | 2.4 | 7.1 | 0.2 | 10.3 | 0.8 | 136.4 | 26.2 | 0.3 | 0.0 |
| 2010 | 9.5 | 2.2 | 10.0 | 1.6 | 8.2 | 0.3 | 10.5 | 1.8 | 110.2 | 17.4 | 0.2 | 0.1 |
| 2011 | 9.8 | 2.3 | 9.8 | 2.1 | 6.7 | 0.3 | 9.1 | 1.0 | 95.5 | 11.7 | 0.2 | 0.0 |
| 2012 | 11.0 | 2.1 | 10.2 | 1.7 | 7.4 | 0.8 | 9.9 | 1.4 | 99.4 | 17.2 | 0.2 | 0.1 |
| 2013 | 10.3 | 2.9 | 10.1 | 2.0 | 7.9 | 0.3 | 11.5 | 0.9 | 100.6 | 14.9 | 0.2 | 0.1 |
| 2014 | 12.2 | 2.4 | 11.3 | 1.7 | 8.1 | 0.5 | 9.7 | 0.6 | 97.8 | 19.2 | 0.2 | 0.1 |
| 2015 | 10.5 | 3.4 | 11.0 | 2.5 | 8.1 | 0.2 | 9.4 | 0.8 | 106.7 | 22.2 | 0.2 | 0.4 |
| 2016 | 11.4 | 2.8 | 11.7 | 1.8 | 7.1 | 0.4 | 10.2 | 1.5 | 111.3 | 20.1 | 0.1 | 0.0 |
| 2017 | 9.6 | 3.0 | 10.2 | 2.3 | 8.2 | 0.4 | 10.9 | 2.2 | 77.8 | 25.6 | 0.3 | 0.1 |
| 2018 | 10.7 | 2.5 | 8.7 | 1.3 | 8.8 | 1.4 | 14.2 | 1.6 | 153.9 | 21.2 | 0.1 | 0.0 |
| 2019 | 11.2 | 2.7 | 11.9 | 2.3 | 8.0 | 0.2 | 8.6 | 0.7 | 129.0 | 25.7 | 0.1 | 0.1 |
| 2022 | 11.7 | 2.5 | 12.2 | 16.0 | 7.5 | 0.3 |
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83.0 | 17.2 | 0.2 | 0.1 |
| 2023 |
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| 2024 | 12.1 | 2.2 | 10.3 | 2.1 | 7.7 | 0.4 | 10.2 | 0.9 | 129.8 | 30.0 | 0.1 | 0.0 |
Table 4. Fall Condition Table
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | Mean | SD | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2008 | 6.3 | 3.0 | 8.8 | 1.3 | 7.3 | 0.4 | 10.5 | 0.4 | 120.2 | 30.9 | 0.4 | 0.1 |
| 2009 | 6.8 | 3.3 | 8.7 | 1.9 | 7.6 | 0.2 | 10.6 | 1.9 | 105.0 | 28.7 | 0.5 | 0.2 |
| 2010 | 4.9 | 4.7 | 7.9 | 2.7 | 7.0 | 0.2 | 9.5 | 0.9 | 110.9 | 31.1 | 0.6 | 0.9 |
| 2011 | 4.9 | 3.0 | 7.0 | 1.8 | 7.3 | 0.6 | 9.7 | 0.5 | 112.7 | 30.1 | 0.3 | 0.3 |
| 2012 | 5.9 | 3.2 | 7.8 | 1.7 | 7.5 | 0.2 | 10.8 | 1.6 | 116.1 | 29.6 | 0.4 | 0.2 |
| 2013 | 6.1 | 3.1 | 8.0 | 2.0 | 7.7 | 0.1 | 10.5 | 0.7 | 119.8 | 30.6 | 0.3 | 0.1 |
| 2014 | 7.3 | 5.0 | 9.6 | 3.2 | 7.9 | 0.2 | 10.0 | 1.2 | 85.3 | 29.8 | 0.3 | 0.1 |
| 2015 | 6.0 | 4.3 | 8.5 | 3.0 | 8.2 | 0.2 | 10.2 | 2.1 | 97.1 | 29.5 | 0.3 | 0.2 |
| 2016 | 7.8 | 3.1 | 9.3 | 1.8 | 8.1 | 1.3 | 9.3 | 1.3 | 54.0 | 9.2 | 0.5 | 0.2 |
| 2017 | 4.8 | 3.3 | 8.4 | 1.9 | 8.1 | 0.7 | 12.8 | 1.4 | 101.8 | 38.2 | 0.3 | 0.2 |
| 2018 | 6.4 | 3.5 | 9.2 | 1.9 | 7.9 | 0.3 | 10.4 | 0.6 | 88.8 | 29.0 | 0.3 | 0.1 |
| 2019 | 5.2 | 3.8 | 8.2 | 2.3 | 7.6 | 0.1 | 11.5 | 1.0 | 103.9 | 26.6 | 0.2 | 0.1 |
| 2022 | 6.9 | 4.9 | 8.4 | 2.5 | 7.8 | 0.2 | 10.1 |
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126.9 | 83.3 | 0.2 | 0.6 |
| 2023 | 8.3 | 5.4 | 9.6 | 2.4 | 7.8 | 0.2 | 10.7 | 0.7 | 66.4 | 66.1 | 0.2 | 0.1 |
| 2024 |
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Figure 2. Spring and Fall Condition Plot
Figure 2. Average daily measures of air and water temperature, pH, dissolved oxygen (DO), total dissolved solids (TDS) and water level (stage) per monitoring year in spring and fall.
2.3. Annual Captures
Since 2008, a total of 5,046 juvenile CCT and 8,216 juvenile Coho Salmon have been captured during spring trapping. Annual captures of CCT have ranged from 45 to 849 (mean = 360) while CO captures have varied from 335 to 913 with an overall mean of 587 fish (Figure 3 and Figure 4, Table 5 and Table 6).
As expected, most fish are captured in the Spring. Catches of CCT have ranged from 45 to 849 during spring (mean = 360 \(\pm\) 276.5) compared to only 1 to 9 fish during fall (mean = 2 \(\pm\) 2.8).
Annual Captures Figures and Tables
Figure 3. Spring - Total annual catches
Figure 3. Total annual catch of CCT and Coho Salmon during Spring fence monitoring.
Table 5. Spring - Total annual catches
## # A tibble: 14 × 21
## # Groups: Year [14]
## Year start end trap_days Date_medCT Date_minCT Date_maxCT nCT FL_meanCT
## <dbl> <chr> <chr> <dbl> <chr> <chr> <chr> <dbl> <dbl>
## 1 2008 Apr-21 May-… 41 May-20 Apr-21 May-31 756 139.
## 2 2009 Apr-19 Jun-… 50 May-16 Apr-20 Jun-03 225 163.
## 3 2010 Apr-19 May-… 42 May-13 Apr-19 May-29 502 150.
## 4 2011 Apr-19 Jun-… 49 May-15 Apr-23 Jun-05 624 155.
## 5 2012 Apr-16 Jun-… 50 May-08 Apr-23 Jun-01 465 160.
## 6 2013 Apr-14 Jun-… 49 May-09 Apr-16 May-30 461 161.
## 7 2014 Apr-24 Jun-… 45 May-09 Apr-27 Jun-02 76 142.
## 8 2015 Apr-10 May-… 52 May-09 Apr-15 May-28 141 158.
## 9 2016 Apr-03 Jun-… 63 Apr-26 Apr-05 May-15 77 147.
## 10 2017 Apr-05 Jun-… 68 May-24 Apr-20 Jun-09 65 185.
## 11 2018 Apr-21 Jun-… 52 May-04 Apr-26 May-27 45 167.
## 12 2019 Apr-18 Jun-… 51 May-06 Apr-18 May-30 571 146.
## 13 2022 Apr-28 Jun-… 47 May-19 Apr-29 Jun-13 189 168.
## 14 2024 Apr-12 Jun-… 55 Apr-29 Apr-17 Jun-03 849 160.
## # ℹ 12 more variables: FL_SDCT <dbl>, FL_minCT <dbl>, FL_maxCT <dbl>,
## # Date_medCO <chr>, Date_minCO <chr>, Date_maxCO <chr>, nCO <dbl>,
## # FL_meanCO <dbl>, FL_SDCO <dbl>, FL_minCO <dbl>, FL_maxCO <dbl>,
## # total.catch <dbl>| Year | Start | End | # Days Sampled | Med. | Min | Max | n | Mean | SD | Min | Max | Med. | Min | Max | n | Mean | SD | Min | Max | n |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2008 | Apr-21 | May-31 | 41 | May-20 | Apr-21 | May-31 | 756 | 139.1 | 27.6 | 90 | 280 | May-17 | Apr-25 | May-31 | 512 | 118.1 | 10.7 | 84.0 | 150 | 1268 |
| 2009 | Apr-19 | Jun-07 | 50 | May-16 | Apr-20 | Jun-03 | 225 | 163.3 | 22.9 | 115 | 265 | May-20 | Apr-24 | Jun-07 | 658 | 100.2 | 11.0 | 11.0 | 160 | 883 |
| 2010 | Apr-19 | May-30 | 42 | May-13 | Apr-19 | May-29 | 502 | 149.7 | 26.1 | 110 | 285 | May-13 | Apr-20 | May-30 | 477 | 118.0 | 15.7 | 80.0 | 183 | 979 |
| 2011 | Apr-19 | Jun-06 | 49 | May-15 | Apr-23 | Jun-05 | 624 | 155.3 | 32.5 | 95 | 400 | May-17 | Apr-20 | Jun-06 | 602 | 113.1 | 12.8 | 80.0 | 147 | 1226 |
| 2012 | Apr-16 | Jun-04 | 50 | May-08 | Apr-23 | Jun-01 | 465 | 160.1 | 33.7 | 80 | 335 | May-13 | Apr-16 | Jun-04 | 689 | 107.8 | 12.4 | 75.0 | 145 | 1154 |
| 2013 | Apr-14 | Jun-01 | 49 | May-09 | Apr-16 | May-30 | 461 | 161.4 | 26.5 | 95 | 350 | May-12 | Apr-15 | Jun-01 | 913 | 106.7 | 9.9 | 83.0 | 150 | 1374 |
| 2014 | Apr-24 | Jun-07 | 45 | May-09 | Apr-27 | Jun-02 | 76 | 142.1 | 29.2 | 70 | 310 | May-12 | Apr-26 | Jun-05 | 376 | 103.2 | 12.4 | 80.0 | 223 | 452 |
| 2015 | Apr-10 | May-31 | 52 | May-09 | Apr-15 | May-28 | 141 | 158.1 | 37.4 | 85 | 260 | May-13 | Apr-11 | May-31 | 761 | 109.3 | 11.7 | 78.0 | 152 | 902 |
| 2016 | Apr-03 | Jun-04 | 63 | Apr-26 | Apr-05 | May-15 | 77 | 147.5 | 37.4 | 88 | 250 | May-05 | Apr-05 | Jun-04 | 817 | 108.0 | 13.4 | 0.0 | 162 | 894 |
| 2017 | Apr-05 | Jun-11 | 68 | May-24 | Apr-20 | Jun-09 | 65 | 185.1 | 64.0 | 120 | 470 | May-20 | Apr-05 | Jun-11 | 335 | 113.4 | 12.8 | 80.0 | 162 | 400 |
| 2018 | Apr-21 | Jun-11 | 52 | May-04 | Apr-26 | May-27 | 45 | 167.4 | 28.2 | 120 | 230 | May-19 | Apr-21 | Jun-11 | 647 | 101.4 | 11.1 | 9.0 | 170 | 692 |
| 2019 | Apr-18 | Jun-07 | 51 | May-06 | Apr-18 | May-30 | 571 | 146.1 | 27.6 | 95 | 260 | May-13 | Apr-24 | Jun-05 | 405 | 115.4 | 12.9 | 10.7 | 152 | 976 |
| 2022 | Apr-28 | Jun-13 | 47 | May-19 | Apr-29 | Jun-13 | 189 | 168.5 | 33.6 | 98 | 430 | May-21 | Apr-28 | Jun-10 | 366 | 113.7 | 13.0 | 80.0 | 170 | 555 |
| 2024 | Apr-12 | Jun-05 | 55 | Apr-29 | Apr-17 | Jun-03 | 849 | 159.8 | 37.1 | 50 | 360 | May-10 | Apr-18 | Jun-04 | 658 | 97.5 | 17.6 | 48.0 | 174 | 1507 |
Figure 4. Fall - Total annual catches
Figure 4. Total annual catch of CCT and Coho Salmon during fall fence monitoring.
Table 6. Fall - Total annual catches
| Year | Start | End | # Days Sampled | Med. | Min | Max | n | Mean | SD | Min | Max | Med. | Min | Max | n | Mean | SD | Min | Max |
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| 2008 | Oct-14 | Nov-22 | 40 | Nov-03 | Nov-03 | Nov-03 | 1 | 440.0 |
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440 | 440 | Nov-02 | Oct-31 | Nov-03 | 5 | 638.0 | 78.9 | 540 | 720 |
| 2009 | Oct-14 | Nov-22 | 40 |
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Nov-03 | Oct-17 | Nov-18 | 12 | 648.3 | 84.1 | 490 | 790 |
| 2010 | Oct-23 | Nov-26 | 35 | Nov-11 | Nov-11 | Nov-11 | 1 | 290.0 |
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290 | 290 | Oct-25 | Oct-24 | Nov-22 | 37 | 640.1 | 91.5 | 405 | 780 |
| 2011 | Oct-18 | Dec-02 | 46 |
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Nov-12 | Oct-26 | Nov-23 | 30 | 650.5 | 82.9 | 370 | 795 |
| 2012 | Oct-14 | Dec-02 | 50 | Oct-28 | Oct-28 | Oct-28 | 1 | 580.0 |
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580 | 580 | Nov-01 | Oct-14 | Nov-20 | 17 | 583.2 | 107.1 | 300 | 690 |
| 2013 | Sep-29 | Dec-01 | 62 |
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Nov-06 | Nov-02 | Nov-18 | 83 | 631.7 | 59.7 | 490 | 790 |
| 2014 | Oct-04 | Nov-30 | 58 | Oct-28 | Oct-28 | Oct-28 | 1 | 430.0 |
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430 | 430 | Oct-28 | Oct-15 | Nov-27 | 91 | 627.8 | 87.8 | 330 | 830 |
| 2015 | Oct-08 | Dec-08 | 62 |
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Nov-08 | Oct-12 | Dec-02 | 77 | 600.0 | 89.4 | 350 | 750 |
| 2016 | Oct-07 | Dec-05 | 60 |
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Nov-01 | Oct-24 | Nov-17 | 9 | 632.8 | 77.9 | 510 | 750 |
| 2017 | Oct-11 | Dec-05 | 56 | Nov-19 | Nov-19 | Nov-19 | 1 | 470.0 |
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470 | 470 | Nov-15 | Oct-18 | Dec-04 | 19 | 592.4 | 133.3 | 330 | 770 |
| 2018 | Oct-08 | Dec-04 | 58 | Nov-01 | Nov-01 | Nov-01 | 1 | 330.0 |
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330 | 330 | Nov-14 | Oct-26 | Nov-28 | 25 | 605.5 | 91.0 | 380 | 790 |
| 2019 | Oct-08 | Dec-10 | 64 | Oct-16 | Oct-16 | Oct-16 | 1 | 390.0 |
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390 | 390 | Oct-25 | Oct-16 | Nov-17 | 22 | 566.8 | 110.2 | 340 | 710 |
| 2022 | Oct-11 | Nov-16 | 37 |
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Nov-03 | Oct-24 | Nov-06 | 125 | 612.7 | 97.5 | 220 | 750 |
| 2023 | Sep-26 | Nov-17 | 45 | Nov-02 | Nov-02 | Nov-16 | 9 | 239.1 | 108.9 | 152 | 430 | Oct-18 | Oct-11 | Nov-16 | 272 | 571.3 | 96.5 | 220 | 740 |
2.4 Length Frequency
The length frequency figures shown below shed light on the population structure and behaviours of Coho Salmon and CCT in Simms Creek. The lengths of CCT (50 mm to 223 mm) and Coho Salmon (48 mm to 223 mm) measured at the fence suggest multiple age classes of juveniles are moving out of the system each spring. Assuming that CO <100 mm are Age 0 and CO >100 mm are Age 1 would suggest that 55.20% of all overall migrants are Age 0 and the remainder are Age 1. A wider range of age classes is likely present among CCT, including Age 0 fish (~<80 mm) up to mature fish > 230 mm and upwards of 3+ years.
Mature CCT >230 mm represent <1.90% of the total catch of CCT. However, all mature CCT >230 mm were moving downstream, suggesting that they either 1) moved upstream and spawned prior to the start of fence operation or 2) had overwintered in Simms Creek and were follow fry out in the spring - whether this was their first movement to the ocean is unknown.
Length Frequency Table and Figures
Figure 5. Length Frequency of all CCT
Figure 5. Length Frequency of all CCT.
Figure 6. Length frequency of Coastal CCT across years.
Figure 6. Length Frequency of CCT across years.
Figure 7. Length frequency of all Coho Salmon.
Figure 7. Length Frequency of All Coho Salmon.
Figure 8. Length frequency of Coho Salmon across years.
Figure 8. Length Frequency of Coho Salmon across years.
2.5 Age Composition
No scale data has been collected during juvenile enumeration work on Simms Creek. However, information collected on systems within the region suggests we can loosely apply the following age classes to juvenile CT and CO:
- CT < 80 ~ Age-0
- CT < 120 ~ Age-1
- CT < 200 ~ Age-2
- CT > 200 ~ Age-2+
- CO < 80 ~ Age-0
- CO < 120 ~ Age-1
- CO > 120 ~ Age-1+
Applying these age bins to the length frequency data suggests that CCT are range in age from Age-1 to Age 3+, but are primarily Age-2 (Figure 9), while CO are almost exclusively Age-1 (Figure 10). Interestingly, Age-0 CO were present in 2009 and 2024, but not other years. While this may be coincidental, it’s worth noting that the peak juvenile CCT counts were recorded in 2008 and 2024. There are a number of mechanisms that may explain why Age-0 CO were first observed in 2024: 1) they weren’t recorded in past years, CO emigrated out of Simms Creek earlier than normal due to high CT abundance.
Figure 9. Age Composition of Juvenile CCT and CO across years.
Figure 9. Assumed age class composition of juvenile CCT and Coho Salmon out migrating from Simms Creek since 2008.
2.6. Migration Timing
2.4.1 Spring Outmigration
Outmigrating juvenile CCT and Coho Salmon were first encountered at the trap over a similar period, from April 05 to April 29 (mean \(\pm\) SD = April 19 \(\pm\) 6 days) for CCT and April 05 to April 28 for Coho (mean \(\pm\) SD = April 18 \(\pm\) 7.3 days). On average 50% of all CCT had passed the fence by May 11\(\pm\) 11.7 days while half of Coho Salmon migrants had passed the fence by May 15\(\pm\) 6.6 days. Despite similarities in when migrations started and the timing that most migrants had past the fence, there was a noticeable difference in the timing of peak migrations (the date when the greatest number of fish passed the fence). For Coastal CCT, the overall mean \(\pm\) SD peak migration occurred on May 07(\(\pm\) 8.2 days) (Figure 5) whereas overall mean peak Coho Salmon migration occurred more than a week later on May 15 (\(\pm\) 7.1 days) (Figure 6). Total number of daily captures of CCT and Coho Salmon per year are presented in Figure 6 and Figure 7, respectively.
2.4.2 Fall Return Timing
Adult Coho Salmon have been detected at the fence as early as October 11 and as late as November 02, though most of the run (50%) arrive within a week of November 05 (Figure 14 to 19). Relative to spring sampling, CCT are encountered less frequently in the fall and arrival timing appears to be considerably more variable (Figure 20 to 22).
Spring and Fall Migration Timing Tables and Figures
Figure 10. Spring - Overall Capture Timing
Figure 10. Overall median spring capture timing.
Figure 11. Spring - Daily captures of CCT per year
Figure 11. Total daily capture of CCT and proportion of total annual captures.
Figure 12. Spring - Total daily captures of Coho Salmon per year
Figure 12. Number of Coho Salmon captured during each day of spring fence operation since 2008.
Figure 13. Fall - Total daily captures of Coho Salmon per year
Figure 13. Number of Coho Salmon captured during each day of fall fence operation since 2008.
Figure 14. Fall - Daily captures of CCT per year
Figure 14. Total daily capture of CCT and proportion of total annual captures.
2.6 What are these fish doing???
CCT show incredible diversity in the timing of their life history behaviours. Throughout their range, spawning has been documented in nearly every month of the year. In Puget Sound for instance, spawning has been reported from November through March and timing is highly variable between years (Losee et al. 2016). The spawn timing of CCT in Simms Creek is unknown, or at least undocumented, however, I would assume it occurs during a similar period to Puget Sound and is equally variable.
The current dataset does provide some insight on spawn timing. Presumably, spawners will be >150 mm in length.
FINISH WRITING THIS SECTION
3. Survival
3.1 What may be driving juvenile abundance
{ 9. Survival, echo = FALSE, warning = FALSE, message = FALSE, include = FALSE} source("SourceFiles/9. Survival.R")
To estimate the number of Coho Salmon that survive from egg to fry, we need to make a number of assumptions:
- All adult Coho Salmon that enter Simms Creek and all juvenile Coho Salmon that outmigrate from Simms Creek are enumerated.
- All adult Coho Salmon that pass the fence will successfully spawn.
- The sex ratio of adults is equal (50% are female, excluding jacks which are assumed male).
- Each female will deposit ~2,600 eggs.Importantly, we also need to consider the proportion of juveniles from each age-class the emigrate each year (and assume juvenile age assignments are accurate). Fish that outmigrate as Age-0 fry will be progeny of fish that spawned the previous fall, while fish that emigrate at Age-1 would have spent a full year in the stream (i.e., spawned 2 falls previous) and Age-1+ fish would have spawned 3 years previous. Using this information, we can then calculate the total number of juveniles produced by each spawning event to calculate egg-to-fry survival.
3.2 What about marine survival (from smolt to spawn)
Additional assumptions are required to estimate the number of juveniles that survive to return as adults:
- Adults spend ~18-20 months at sea (1 winter), regardless of whether they leave Simms Creek as Age-0 or Age-1.
- Jacks return to Simms Creek after ~6-8 months at sea (0 winters).
- All Coho Salmon that are enumerate at the fence originated from Simms Creek (i.e., there are no hatchery fish or strays from neighbouring streams).##————————–